Seafood prices reveal impacts of a major ecological disturbance

Coastal hypoxia (dissolved oxygen ≤ 2 mg/L) is a growing problem worldwide that threatens marine ecosystem services, but little is known about economic effects on fisheries. Here, we provide evidence that hypoxia causes economic impacts on a major fishery. Ecological studies of hypoxia and marine fauna suggest multiple mechanisms through which hypoxia can skew a population’s size distribution toward smaller individuals. These mechanisms produce sharp predictions about changes in seafood markets. Hypoxia is hypothesized to decrease the quantity of large shrimp relative to small shrimp and increase the price of large shrimp relative to small shrimp. We test these hypotheses using time series of size-based prices. Naive quantity-based models using treatment/control comparisons in hypoxic and nonhypoxic areas produce null results, but we find strong evidence of the hypothesized effects in the relative prices: Hypoxia increases the relative price of large shrimp compared with small shrimp. The effects of fuel prices provide supporting evidence. Empirical models of fishing effort and bioeconomic simulations explain why quantifying effects of hypoxia on fisheries using quantity data has been inconclusive. Specifically, spatial-dynamic feedbacks across the natural system (the fish stock) and human system (the mobile fishing fleet) confound “treated” and “control” areas. Consequently, analyses of price data, which rely on a market counterfactual, are able to reveal effects of the ecological disturbance that are obscured in quantity data. Our results are an important step toward quantifying the economic value of reduced upstream nutrient loading in the Mississippi Basin and are broadly applicable to other coupled human-natural systems.publishedVersio

The São Paulo wholesale seafood market: A study of fish prices in Brazil.

We analyze fish pricing in the São Paulo wholesale market, the second largest seafood market in South America. Quantitative price analysis is complemented by interviews with participants in the value chain to answer how the multitude of fish products supplied in this market are related and the challenges facing future growth. The results reveal a clear separate pricing of domestically produced fishery species (whitefish and pelagics) from the internationally traded aquaculture species (tilapia and salmon). Tilapia and salmon are uniquely priced, less volatile and more persistent with a price dynamic more akin to local terrestrial meats. Fishery prices show large month-by-month fluctuations and compete more with each other. Participants in the different levels of the value chain corroborate the uniqueness of salmon and state a preference for stable availability and low prices, with less concern about the specific sourcing of fish (aquaculture/fisher, or domestic/imported)